Seems like the skill needs a lot of semantic knowledge. This is less coding than a meta game.
A game template looks something like this: https://gist.github.com/jamesfdickinson/65b9f5a05f4902468c46...
I plan to add more game templates with the create object command for more advanced users. You can set it's properties, game physic values and so on. The game itself will need to implement and execute that command. The game template just tells the Game Creator what that current game supports. So the magic happens in the game code. Hit view source on the game if want to see it.
The project was built in a 2 weeks; server, Alexa integration, mini-game, and game creator logic. If the project gets any traction, I'd love to keep working on it.